In the United States, bioethanol is produced by fermentation from sources such as corn at over 100 commercial facilities, and these facilities may also be utilized to commercialize biobutanol technology that involves similar fermentation and distillation operations. Butanol is an alcohol with a variety of applications, such as a fuel additive, a blend component to diesel fuel, a chemical reagent in the plastics industry, and a food grade extractant in the food and flavor industry. Butanol is favored as a fuel or fuel additive because it has a higher energy density than ethanol and yields only CO2 and little or no SOX or NOX when burned in the standard internal combustion engine. Additionally, butanol is less corrosive than ethanol. Each year ten to twelve billion pounds of butanol are produced by petrochemical means. As the projected demand for butanol increases, interest in producing butanol from renewable resources such as corn, sugar cane, or cellulosic feeds by fermentation is expanding.
Converting a facility from bioethanol to biobutanol production may involve, for example, retrofitting the equipment and configuration to enable fermentation and purification of butanol; and an objective of this conversion may be minimal use of capital. Retrofitting the equipment may include both modification of existing equipment and installation of new equipment. To minimize loss of operational flexibility, the conversion to a biobutanol plant may be reversible. For example, if there are fluctuations in the biofuel market, the ability to restore the facility to a bioethanol production plant would be advantageous. Depending on circumstances, the facility may revert to its original state prior to the conversion to a biobutanol plant or improvements may also be incorporated in the reversion to a bioethanol production plant. It would also be beneficial to have the ability to convert the reverted bioethanol production plant to a biobutanol production plant, for example, if the demand for bioethanol changes. That is, the retrofit of the bioethanol production plant may be reversible, allowing the facility to be easily converted between a bioethanol production plant and a biobutanol production plant, for example, with little or no loss of operations. Furthermore, in the construction of a biobutanol production plant, it would be advantageous to also incorporate the ability to convert the biobutanol production plant to a bioethanol production plant. If the demand for a biofuel changes, a biofuel production plant that could easily be converted to produce biobutanol, bioethanol, or other biofuel would be valued.
Thus, there is a need for processes and systems for producing butanol using a retrofit of a bioethanol production plant or a newly constructed biobutanol production plant, and a need for processes and systems that may be easily converted to either a bioethanol production plant or a biobutanol production plant. The present application satisfies these and other needs, and provides further related advantages, as will be made apparent by the description of the embodiments herein.